Field Of The Invention
The present invention aims at providing a method, a process and a plant for controlling building of tyres for vehicle wheels.
Description Of The Related Art
A tyre for vehicle wheels generally comprises a carcass structure comprising at least one carcass ply having respectively opposite terminal zones respectively engaged to annular anchoring structures, generally referred to as “bead cores”, integrated in the areas usually referred to by the name “beads”, having an inner diameter substantially corresponding to a so-called “rim diameter” of the tyre on a respective mounting rim. The tyre also comprises a crown structure comprising at least one belt strip located in a radially outer position with respect to the carcass ply and a radially outer tread band with respect to the belt strip. Between the tread band and the belt strip is there may be interposed a so-called “underlayer” made of elastomeric material with properties suitable to guarantee a stable union of the belt strip/strips with the tread band itself. On the lateral surfaces of the carcass structure, each extending from one of the lateral edges of the tread band up to the height of the respective annular anchoring structure to the beads, there are also applied respective sidewalls made of elastomeric material. In the tyres of the “tubeless” type, the carcass ply is internally covered by a layer of elastomeric material preferably butyl-based, usually referred to as “liner” having optimal air impermeability characteristics and extending from one bead to the other.
The expression “elastomeric material” is used to indicate a composition comprising at least one elastomeric polymer and at least one reinforcing load. Preferably, such composition additionally comprises additives such as, for example, a cross-linking and/or a plasticising agent. Due to the presence of the cross-linking agent, such material can be cross-linked by heating, thus forming the final product.
The expression “intermediate portion of the carcass structure” is used to indicate at least one carcass ply.
The expression “completion locations” is used to indicate one or more locations comprising apparatuses adapted to deposit new components and/or shape the previously deposited components. For example, the following can be provided for: a location comprising a tyre bead-forming station and a location comprising a rolling station, possibly integrated in the tyre bead-forming station. Preferably the completion locations and the relative apparatus are fixed, indicated with the term “fixed” locations/apparatus which are not subjected to a transfer through movements related to the type of processing carried out, for example rotations, lifting and/or lowering to adapt to the diameter of the tyre, contraction and expansion movements, being allowed.
The expression “transfer location” is used to indicate one or more locations in which the forming drum for a subsequent processing is made available. For example a first transfer location operatively disposed between an intermediate forming line and at least one completion location may be provided. The first transfer location may for example be reached by a moveable shuttle along the intermediate forming line. Furthermore a second transfer location operatively disposed between at least one completion location and a station of assembling the crown structure, may be provided for. The second transfer location may for example be reached by a moveable shuttle. A transfer location may be fixed or variably identifiable along a trajectory of a shuttle.
The term “trajectory” is used to indicate a path covered for example by a handling device and/or one or more shuttles for transferring a forming drum. It may be a rectilinear or broken trajectory. The same trajectory may be defined by one or more shuttles.
The expression “operating moment” is used to indicate a operating instant of the plant.
Document EP 0 555 813 in the name of the same Applicant discloses a plant for building carcass structures far vehicle wheels comprising a plurality of building drums moved along an assembling path. Each drum meets, according to a predefined succession, a number of primary work stations, each adapted to apply a respective common main component to a plurality of carcass types, alternated with auxiliary work stations adapted to apply accessory components. Each auxiliary work station may be removed and replaced with a different station according to the type of process to be performed and it is moveable between a rest position, in which it is perpendicularly moved away from the assembling path, and a work position, in which it is operatively disposed along the assembling path, for performing the application of the respective accessory component. The primary work stations may be mutually approached or moved away along the assembling path.